Method of perforating a heated billet and disc



METHOD OF PERFORATING A HEATED BILLET AND DISC Filed Aug. 14, 1952 J. BUFFET Oct. 9, 1956 2 Sheets-Sheet 1 IN VE/VTOR. Jean Buffet v- H/S ATTORNEYS Get. 9, 1956 J. BUFFET 2,765,528

METHOD OF PERFORATING A HEATED BILLET AND DISC Filed Aug. 14, 1952 2 Sheets-Sheet 2 M g" E L 1 T7 7 f 5 United States Patent C fiice 2,765,528 Patented Oct. 9, 1956 METHOD OF PERFORATING A HEATED BILLET AND DISC Jean Buffet, Beaumont-sur-Oise, France, assignor to Comptoir Industrial dEtirage et Profilage de Metaux, Paris, France, a corporation of France Application August 14, 1952, Serial No. 304,382 Claims priority, application France August 22, 1951 2 Claims. (Cl. 29539) This invention relates to a method of perforating metal billets by forcing a perforating element axially through the billet, more particularly with the object of forming perforated billets or blanks for the subsequent hot extrusion of tubes by placing between each billet and its support a low-cost metal disc that has been heated to a lower temperature than that of the billet.

In the accompanying drawings which illustrate a preferred embodiment of my invention,

Figure l is a partial longitudinal section through a perforating press, the parts being shown in the positions which they occupy at the beginning of a perforating operation;

Figure 2 is a view similar to Figure 1, the parts being shown in the positions which they occupy near the end of a perforating operation;

Figure 3 is a longitudinal section through a composite billet used according to my method, the composite billet being shown before the perforating step;

Figure 4 is a longitudinal section through the composite billet after the perforating step;

Figure 5 is a section of the punched out portion of the perforated composite billet; and

Figure 6 is a section through a modified form of disc of inexpensive metal.

According to a known method of perforating a billet, a heated billet is placed in a container and While the billet is supported at one end, a perforating element is forced axially through the billet from its opposite end to partially perforate the billet. During such perforation, the metal of the billet is displaced in a direction parallel to the axis of the billet and away from the support, or in some cases, the metal of the billet is displaced in a direction perpendicular to the billet axis and then in a direction parallel to this axis and away from the support, depending upon the particular conditions employed.

In carrying out such perforating operation, it is not possible to force the perforating element completely through the entire length of the billet and into contact with the billet support. Toward the end of the perforating step, the pressure increases greatly, thereby either stopping the perforating element in its stroke, or else subjecting it to excessively heavy strains. In order to overcome these objectionable features which occur toward the end of the perforating step, perforating presses are equipped with end-of-stroke devices which limit the stroke of the perforating element and are so adjusted that the perforating element leaves an unperforated portion of the billet adjacent the billet support, which is of constant and minimum thickness. This unperforated portion is then punched out by removing the billet support and forcing the perforating element through the remaining portion of the billet. This punched out portion, even though of minimum thickness consistent with safe operation of the perforating press, still results in an appreciable loss of punched out billet metal. Where the billet which is being perforated is made of stainless steel or other high cost metal or alloy, the cost due to the loss of the punched out portions is considerable.

I have invented a method whereby the loss of high cost billet metal, for example stainless steel, in the punched out portion of the billet is very substantially reduced. In fact, according to my method, the punched out portion of the billet may consist almost entirely, if not entirely, of low cost metal, substantially all of the high cost metal of the original unperforated billet remaining in the billet after perforation.

Referring more particularly to the accompanying drawings, a billet 2 of stainless steel or other high cost metal or alloy which is to be perforated is shown in a container 3 of a perforating press. A disc 4 of plain carbon steel or other relatively cheap metal is welded to the bottom of the billet 2 or is placed loose in the container between the bottom of the billet and the top of a billet support which comprises an outer portion 5 and a separate inner portion 6. The parts 5 and 6 form a bottom for the container 3. The portion 5 of the bottom is supported by a member 7 and the inner portion 6 of the bottom is supported by a member 8, the arrangement being such that the entire bot-tom consisting of the portions 5 and 6 can be raised into the position shown in Figure 1 so as to support the billet 2 or, when desired, the inner portion 6 of the bottom can be lowered for a purpose hereinafter described.

The perforating press also comprises a perforating element having a head 9 secured to a rod 10 which may be reciprocated axially of the container by means not shown. The rod 10 is slidable through a guide block 11 which fits within the container while allowing the rod 10 and head 9 to move up and down in the container during the perforating operation. Guide-block 11 is pressed against the upper face of the billet by means of a jack-head 12 before beginning the perforation.

The following is a specific example of my method.

A plain carbon steel disc 4 was welded to the bottom of a stainless steel billet 2, and the composite billet was placed in the container 3 with the bottom 5-6 in the position shown in Figure l. The stainless steel billet 2 contained 18% chromium, 10% nickel and 0.03% carbon. It is well known to those skilled in the art that the plain carbon steel disc is more readily deformable than the stainless steel billet. The billet had a length of 300 mm., and a diameter of mm. The composite billet was heated to a temperature of 1300 C. before it was placed in the container. The container 3 had an internal diameter of mm. The head 9 of the perforating element had a diameter of 105 mm.

The perforating head 9 was then forced downwardly into the billet 2, thereby forming the axial perforation 14. Because the lower end of the billet was supported by the bottom 5-6 during movement of the perforating head 9 into the billet, the metal of the billet flowed perpendicularly to the billet axis until the billet was compressed, and then it flowed in a direction parallel to this axis and toward the top of the container 3. When the perforating head 9 had reached the limit of its downward stroke as shown in Figure 2, there still remained an unperforated portion located below the perforation 14, which unperforated portion was made up of a relatively thick layer 4a of the disc metal 4 which was plain carbon steel, and a relatively thin layer 2a of stainless steel. This unperforated portion consisting of the layers 4a and 2a was then punched out of the billet by first lowering the bottom portion 6 and its support 8 relative to the outer bot-tom portion 5, and then moving the perforating head 9 downward a further distance to complete the punching out operation. The punched out portion is shown in Figure 5. The stainless steel part 2a weighed 0.5 kg., and the plain carbon steel part 4a weighed 1 kg.

If no'disc' 4ha'dbeen eniployed, the punching would weighed 1.5 kg. Thus by following my method, the loss of stainless steel in the punching was reduced to onethird of what it would have been, had-the disc 4 of plain carbon steel not been used.:

In' order to reduce to a minimum the loss of: stainless steel or other high cost metal which is'lost in the punching, the disc 4 is notwelded to the billet but is heated separately from the billet 2 to a temperature lower than that to which the billet is heated for perforating. In this manner, resistance of the disc 4-to deformation is increased, and thisreduces the loss in the metal of -which the billet 2 is made. By heating the disc 4-to -a lower,

temperature than thebillet 2,,the disc will be flattened less during the perforating stepthanwould otherwise be the case, therebyresultingin adisc which at the end of the perforating-step isthick'er than if the disc and billet were heated to the same temperature.- Since the disc will be thicker, for the same stroke of-the perforating head 9,

the unperforating portion 2a will-bethinner andthe loss of metal of the billet 2will be less. 7

Another way of minimizing the loss of high cost metal in the punching is' to use a disc 4 which has a greater thickness at its center than at its edges, an example of such'clisc being shown in Figure 6 and designated by reference numeral 4b. Referring to Figures 2 and' 4, it

fore, for thesame stroke of the perforating head 9, the

unperforated portion 2a of the billet will be thinner.

It is not necessary to weld or otherwise secure the disc 4 or 4b to the billet. The disc may simply be placed on'"the bottomS-fibefore the bi'llet'isin'serted into the ta n r- If for any other reason than cost of billet metal, it is desired to reduce the discard of billet metal to a minimum, this invention is applicable.

The invention is not limitedto the preferred embodiment, but may be otherwise embodied or practiced within the 'scope of'th'e following claims.

What I claim is:

1. In a method of perforatingbillets of high-cost metal by supporting one end of'the heatedbillet on asupport while forcing a perforating-memberaxially through said billet from its opposite end so as to partly perforate the billet by displacing metal towards said opposite end, leaving an-unperforated portion of said billet adjacent-said support, and there'aftercontinuing th emove ment of said perforating member to punch' oufitlfeninperforated portion from which the support has been withdrawn, the improvement comprising placing between said support and theadjacent'end of said billet, prior to the perforating step, a disc of low-cost metal, said disc-being more readily deformable at the perforating temperature than the said billetand being heated prior to the perforating step to a temperature lowerthanthat of said billet, whereby the punched-out portion-0f said billet consistssubstantially of low-cost metal only and waste of said high-cost metal is greatly reduced.

2. A method as claimed in claim 1 in which the said high cost metal is stainless steel and the said disc is of ordinary carbon steel.

References Cited in the file of this patent UNITED STATES PATENTS Re. 2 1,433 Pederson Apr;'23, 1940'- 2,422,052 Temple June 10, 1947 2,423,432 Barlow July 8,1947 2,586,336 HuCk'- Feb, 19, 1952' FOREIGN PATENTS 92,825 Germany- July 29, 1897 497,270 Great Britain Dec. 15, 1938 

